Electrically and chemically heated crucible



(No Model.) 2 Sheets-Sheet 1.

H. G. ONEILL. ELEGTRIGALLY AND GHEMIGALLY HEATED GRUGIBLE.

No. 538,271. Patented Apr. 30, 1895.

(No Model.) 2 Sheets-Sheet 2.

H. G. ONEILL. ELEGTRICALLY AND UHEMICALLY HEATED URUCIBLE. NO. 538,271.Patented Apr. 30,1895.

|||||ll H UNITED STATES PATENT OFFICE.

HENRY G. ONEILL, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO EDWARD JEWELL, OFSAME PLACE, AND CHARLES \V. WELOH, OF STOUGHTON MASSACHUSETTS.

ELECTRICALLY AND CHEMICALLY HEATED CRUCIBLE.

SPECIFICATION forming part of Letters Patent No. 538,271, dated April30, 1895.

Application filed March 24,1894. Seria1ITm504a9 (No model.)

To all whom it may concern.-

Be it known thatI, HENRY G. ONEILL, a citizen of the United States,residing at Boston, in the county of Suffolk and State of Massachusetts,have invented certain new and useful Improvements in Electrically andChemically Heated Orucibles Containing Rheostats; and I do herebydeclare the following to be a full, clear, and exact description of theinvention, such as will enable others skilled in the art to which itappertains to make and use the same.

This invention relates to the art of heating by electrical and chemicalmeans, that is to say by'means in which the electric current generatesheat by the combustion or other chemical action which it causes orfacilitates, as well as directly by overcoming the resistance ofconductors and other purely physical methods of heat-evolution. Moreespecially this invention relates to electrically and chemically heatedcrucibles and other like articles, in which a very high temperature isnecessary for the reduction of their contents. This invention isdesigned to produce high tempera tures, readily controlled, with theleast possible outlay of energy.

Heretofore, in devices of this character, owing to the inconstancy ofthe resistance, it has generally been found necessary to use liquidrheostats, in which, on an average, one half of the total energyemployed was lost; not more than half being utilized in the crucibleitself. Finely pulverized material of a carbonaceous nature has beenused in such crucibles as a resistance, but it has been open Myinvention remedies the above defects,

dispensing with the need for a liquid rheostat, avoiding the productionof clouds of carbonaceous material, and locking in and utilizing almostall the heat that is generated.

To these ends my said invention consists in the construction andcombination of parts, hereinafter particularly set forth and claimed. Inthe accompanying drawings, Figure 1 represents a frontelevation of anelectrochemically heated crucible or small furnace embodying myinvention. Fig. 2 represents a vertical central section through thesame. Fig. 3 represents a horizontal section on the line :15oc of Fig.2. Fig. 4 represents a front elevation of the interior receptacle orcrucible proper and the wire resistance wound thereon; and Fig. 5represents a diagram of the circuits and regulating devices the exteriorreceptacle being shown in section and a contact arm being shown of aslightly different form from that in Fig. 1.

A designates this crucible or inner receptacle which may have anyconvenient form and consists of a mixture of diatomaceous earth andkaolin or fire clay molded and fired as is usual in pottery making.Molded asbestos may be substituted therefor. At diametrically oppositepoints two recesses A A are formed in its inner face to receive and holdthe bar electrodes 13 and B, preferably of compressed carbon, which areinterchangeable and renewable.

0 represents an outer receptacle of non conducting material, largeenough to leave a space 0' between it and the sides and bottom of theinner receptacle A, which space is filled with diatomaceous earth 0 orsome other comminnted insulating and fire proof material. 'lhe tops ofthe two receptacles A and O are on a level.

A resistance D of wire, carbon or other conducting material is woundaround the inner receptacle A, one of its ends being connected toelectrode B while the other end is connected to the contact plate Ghereinafter described. The other electrode B is in connection with wireE one of the feed wires of an ance.

electric circuit. Fromthe other feed wire E of the said circuit a wire Eextends to a movable switch or contact arm H hereinafter described. Thisat will is in contact with plate G; and the circuit is completed througha conducting mediumF which is placed within the receptacle A so as to bein contact with the said electrodes. For this conducting medium F Iprefer to employ lamp-black mixed with diatomaceous earth though otherforms of carbon may be used in this mixture; the amount of the latterregulating the resistance of the mixture, and also the increase thereoftending to keep such resistance more constant as the temperatureincreases. The mixture of diatomaceous earth prevents the surroundingair from being clouded by particles of carbon, in filling the crucibleand when they are agitated by the escaping products of combustion.

WVhen lime or similar material is employed, mixed with carbon of anykind, so great is its decomposition when highly heated that thecontinuity of operation is interrupted and a uniform and steady heatingcannot be obtained, owing to the rapid generation of gas that forces itsway upward, disturbing the resistance, and always interrupting thecurrent partially or wholly. By the use of diatomaceous earth in themixture instead of lime all the disadvantages are eliminated and theobjections above stated are overcome.

To regulate at will the resistance surrounding the inner receptacle A Iprovide the outer receptacle 0 with a series of contact plates G G2 G 6*G which are connected by wires g to the resistance D at different pointsof its length. The outside of the said receptacle A is also providedwith a pivoted contact arm II which may be shifted from one of theseplates to another for the purpose of cutting out more or less of thesaid resistance from the circuit. The contact plate G2 which providesfor the maximum resistance, usually about four ohms, is connected by itswire 9 with one end of the resistance D, the other end of the saidresistance being connected to a feed wire, while the contact arm H isconnected to another feed wire in the same circuit which is closedthrough the said resist Of course the regulating of the amount ofresistance by shifting the said arm increases or decreases at will theavailable strength of current and the heat producing effect. The contactend of the said arm H is shown bifurcated in Fig. 1 so as to rest on twocontact plates at once; but this is not necessary. The current will ofcourse be directed through the plate communicating with the lessresistance. A lid I may be employed for the said inner receptacle orcrucible A, being preferably composed of earthenware or other refractorymaterial.

Spacing pieces J are inserted between the inner and outer receptacles Aand B, being supported by the diatomaceous earth 0 in the space 0 whichlatter they maintain of equal width at all points.

A tube or passage K, extending from the outside of the outer receptacleto the inside of the inner receptacle, allows the insertion of rods orother articles the ends of which are to be heated; or m uli'les may berun in through this passage and withdrawn also through the same; or anysuitable vessel F containing a substance to be acted on by intense heatmay be introduced within the said inner receptacle and crucible andwithdrawn therefrom at will.

The operation is as follows: When the electric current is turned on, itleaps from particle to particle of the mixture F which is in a veryminute state of subdivision. Molecular arching is really established.Under this action the carbon in mixture F becomes incandescent veryquickly. The atmospheric oxy gen unites with the carbon and theresulting gas ignites, giving the heat of combustion also. To this isadded the heat of resistance from the resistance D. So intense is theheat thus produced that carbon itself is vaporized, showing thetemperature to be over 3,000 centigrade.

I find by experience that thereduction of the most refractory metal orore on a small scale may be accomplished at an outlay of about twelvehundred Watts of energy.

The devices hereinbefore described may be used for electric and chemicalheating purposes wherever applicable, as well as for crucibles and othermetal reducing apparatus.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent, is

1. In an electro-chemical crucible or furnace a mixture of diatomaceousearth and carbonaceous material with a containing receptacle andelectric circuit connections arranged and adapted to send a current ofelec tricity through the said mixture substantially as set forth.

2. The combination of a crucible or receptacle with electrodes containedtherein, electrical circuit connections to the said electrodes and amixture of diatomaceous earth and carbonaceous material interposedbetween the said electrodes substantially as set forth.

3. In combination with a mixture of diatomaceous earth and carbonaceousmaterial and electrical connections making circuit through such mixture,a receptacle containing the same, a resistance wound on the saidreceptacle and electrical circuit connections through the saidresistance substantially as set forth.

iyln combination with a receptacle and a mass of comminuted conductingmaterial contained within the same, a resistance wound on the saidreceptacle a movable contact arm and series of contact plates and theirconnections for cutting more or less of the said resistance out ofcircuit, and electrical conduca current through the same substantiallyas tors making circuit through the said resistset forth. :0 ance and thesaid mass substantially as set In testimony whereof I aifix my signatureforth. in presence of two Witnesses.

5. In electro-chemical heating devices, the HENRY G. ONEILL. [L. s]combination of a conuninuted mixture of dia- Witnesses: tomaceous earthand carbonaceous material CARL F. A. SIEDHOF,

with electric circuit devices arranged to send PELATIAH R. TRIPP.

